/Engine/Plugins/FX/Niagara/Source/NiagaraEditor/Public/ViewModels/Stack/NiagaraStackFunctionInput.h
Gets the function node form the script graph if the current value mode is DefaultFunction.
[UNiagaraNodeFunctionCall](API\Plugins\NiagaraEditor\UNiagaraNodeFunctionCall) * GetDefaultFunctionNode() const